1. Field of the Invention
The present invention relates to a method of fabricating an organic light emitting display and, more particularly, to a method of fabricating an organic light emitting display including forming a donor substrate attached to a frame to transfer the donor substrate, when an organic layer pattern is formed by a laser induced thermal imaging (LITI) method.
2. Description of the Related Art
Generally, an organic light emitting display (hereinafter, referred to as OLED) as a flat panel display includes anode and cathode electrodes, and organic layers interposed between the anode and cathode electrodes. The organic layers include at least an emission layer, and may further include a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer, in addition to the emission layer. This OLED is classified into a polymer OLED and a low molecular OLED depending on a material for forming the organic layer, especially, the emission layer.
In the OLED, in order to realize full color displays, the emission layer should be patterned. The emission layer can be patterned by a method using a shadow mask in the case of the low molecular OLED, and by an inkjet printing method or an LITI (laser induced thermal imaging) method in the case of the polymer OLED. Among them, the LITI method may finely pattern the organic layer and has an advantage of realizing high-resolution and large-sized displays, and may employ a dry etching process unlike the inkjet printing method employing a wet etching process.
The method of forming the organic layer pattern using the LITI method requires at least a light source, an OLED substrate and a donor substrate. Patterning the organic layer on the substrate is performed as light emitted from the light source is absorbed into a light-heat conversion layer of the donor substrate to be converted to heat energy and a material for forming a transfer layer is transferred on the substrate by the heat energy. These are disclosed in Korean Patent Application No. 1998-51844 and U.S. Pat. Nos. 5,998,085, 6,214,520 and 6,114,088.
At this time, since a process of laminating the donor substrate on the substrate is required, the donor substrate was deposited on the substrate using a lamination roll in a conventional art. That is, after winding the donor substrate, at which the transfer layer was formed, on the lamination roll, the donor substrate is cut and moved, and then the donor substrate wound on the lamination roll is unwound to be deposited on the substrate. The lamination method is very simple, but there is a problem of deteriorating the characteristics of the OLED. That is, there may be generated crack or contaminants such as particles generated while the flexible donor substrate is wound on the lamination roll. In particular, since a process of forming the transfer layer in the donor substrate and a lamination process for the LITI are separately performed, there is a problem of deteriorating the characteristics of the OLED due to contaminants such as particles and so on, which may be generated between both processes.